Conventionally, in an attitude angle estimating device that estimates attitude angles of a vehicle by using in-vehicle angular velocity sensors and acceleration sensors, because the zero point drifts of the in-vehicle angular velocity sensors and acceleration sensors greatly affect the estimation of the attitude angles, there is the need to successively estimate and compensate the zero point drifts.
As conventional techniques that estimate the zero point drift of such a sensor, there are known a technique (for example, Patent Document 1) that, when the sensor output is within a threshold value for greater than or equal to a uniform time, judges that an object is stationary and makes the sensor output value at this time be the sensor drift amount, and a technique (for example, Patent Document 2) that, when the left-right difference of the wheel speeds is small, judges there to be a straight traveling state, and makes the lateral acceleration at this time be the lateral acceleration sensor drift amount, and the like.